One hundred and ninety-two (18.5%) specimens tested by NREVSS laboratories in Texas were positive for influenza. Six specimens were positive for 2009 influenza A (H1N1), 28 specimens were positive for influenza A (H3N2), 1 specimen was positive for influenza A (not subtyped), and 7 specimens were positive for influenza B by PCR testing; the remaining positive results were obtained by antigen detection test.

The percentage of visits for influenza-like illness as reported by ILINet providers in Texas was below the state and regional baselines.

One influenza-associated pediatric death was reported.

One influenza outbreak in a long-term care facility was reported.

Reports from Health Service Regions

Reports were received from all Health Service Regions (HSRs) for week 1. HSRs 1, 4/5N, 7, 8, and 11 reported an increased level of flu activity compared to week 52. HSRs 6/5S and 9/10 reported the same level of flu activity compared to week 52. HSR 2/3 reported a decreased level of flu activity compared to week 52. For a map of Health Service Regions please visit the following website: http://www.dshs.state.tx.us/regions/state.shtm

Laboratory Results

Influenza

During week 1, seven hospital laboratories and public health agencies across Texas reported conducting a total of 1,038 influenza tests (antigen, culture, and PCR) to the National Respiratory and Enteric Virus Surveillance System (NREVSS) sponsored by the Centers for Disease Control and Prevention (CDC). Seventy-five percent of the influenza tests reported to NREVSS were antigen detection tests; these tests cannot identify the subtype of influenza detected. The results from Texas participants in NREVSS are summarized in the table below.

Testing Information

Week 1

No. of specimens tested

1,038

No. of positive specimens (%)

192 (18.5%)

Positive specimens by type/subtype

Influenza A

160 (83.3%)

Subtyping performed

34 (21.25%)

A (2009 H1N1)

6 (17.6%)

A (other H1N1)

0 (0%)

A (H3N2)

28 (82.4%)

Subtyping not performed

126 (78.75%)

Influenza B

32 (16.7%)

Additional influenza test results (rapid tests, culture, PCR) were reported from providers and public health departments throughout the state (see county map at the end of this report).

Other Respiratory Viruses

The NREVSS system collects information on a variety of respiratory viruses in addition to influenza including parainfluenza, respiratory syncytial virus (RSV), rhinovirus, human metapneumovirus (HMPV), and respiratory adenovirus. The results from week 1 are summarized below.

Virus

Number of Laboratories Testing

Tests Performed

Positive Tests

Percentage of Tests Positive

Adenovirus (respiratory)

3

198

13

6.57%

HMPV

3

151

3

1.99%

Parainfluenza

3

198

4

2.02%

Rhinovirus

2

135

23

17.04%

RSV

11

862

208

24.13%

Antigenic Characterization

Since July 2010, CDC has reported antigenic characterization results from 3 influenza A (H1N1) viruses, 14 influenza A (H3N2) viruses, and 7 influenza B viruses received from the Texas Department of State Health Services (DSHS) Laboratory.

Influenza A (H1N1) [3]Three viruses were related to A/California/07/2009-like (H1N1), the influenza A (H1N1) component of the 2010-2011 influenza vaccine for the Northern Hemisphere.

Influenza A (H3N2) [14]Fourteen viruses were related to A/Perth/16/2009-like (H3N2), the influenza A (H3N2) component of the 2010-2011 influenza vaccine for the Northern Hemisphere.

Influenza B [7]

Victoria lineage [7]Seven influenza B viruses were related to B/Brisbane/60/2008-like, the influenza B component of the 2010-2011 influenza vaccine for the Northern Hemisphere.

Yamagata lineage [0]No influenza B viruses of the Yamagata lineage have been characterized since 2009.

The national antigenic characterization and antiviral resistance testing results may be found in the final CDC weekly flu report at www.cdc.gov/flu/weekly/. The DSHS Laboratory sends a representative sample of influenza viruses to the CDC throughout the flu season.

Antiviral Resistance

Since July 2010, CDC has not reported any antiviral resistance testing results on influenza isolates received from Texas laboratories.

Influenza–Associated Pediatric Mortality

One influenza-associated pediatric death occurred during week 1 in a 14-month-old resident of HSR 2/3 with no underlying medical conditions. A specimen collected from the child was positive by PCR testing for influenza A (H3N2). The child had not received influenza vaccine during the current season. Two influenza-associated pediatric fatalities have been reported in Texas since the beginning of the 2010-2011 influenza season. One death has been reported during calendar year 2011. Please see the table below for more information.

Influenza-Associated Deaths in Pregnant and Postpartum Women

No new influenza-associated deaths were reported in pregnant or postpartum women during week 1.

DSHS is requesting reporting of influenza-associated deaths in pregnant or postpartum (up to 6 weeks) women during the summer of 2010 and continuing throughout the 2010-2011 influenza season. There has been 1 death reported since the beginning of the summer 2010. All influenza types and subtypes should be reported; a positive rapid influenza test is sufficient for confirmation.

School Closures and Institutional Outbreaks

One influenza outbreak in a long-term care facility in HSR 7 was reported during week 1. Several of the residents tested positive for influenza A by rapid test. Information on the control of influenza in various settings may be found on the CDC website at http://www.cdc.gov/flu/professionals/infectioncontrol/.

U.S. Outpatient Influenza-like Illness Surveillance Network

Sixty-two providers in Texas reported data to the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) (formerly known as the U.S. Influenza Sentinel Provider Surveillance System) on patients with influenza-like illness (ILI) and total patients seen for any reason during week 1. Of the 61 providers who saw patients, 48 (79%) saw at least one patient with ILI. Of all patient visits during this week, 4.11% were due to ILI. The Texas ILI baseline is 6.09% for the 2010-2011 season. The ILI baseline for HHS Region 6 (Arkansas, Louisiana, New Mexico, Oklahoma, and Texas) of the United States is 4.9% for the 2010-2011 season. The baseline is the mean percentage of patient visits for ILI during non-influenza weeks for the previous three seasons plus two standard deviations. The baselines displayed on the graph below were calculated for the official influenza reporting season only (approximately October to May).